Marc,
I have heard it as: a company cannot expand faster than the GDP for infinity and growth has to eventually equal the GDP (or less).
Put this way the alternative is to believe that the company will eventually crowd out the entire economy. You occasionally see the fantasy nightmare in science fiction movies. A drug so addictive or the price of immortality where nothing else matters. But even here the growth ends up equaling the GDP.
Back to the real world, I do not think even Apple will consume all of our dollars into the future.
-Jim